The A-35 (a highway in Quebec) has been under construction since 1966. When finished, it will be 34 miles/55 km long.
Two decades isn't very long for an infrastructure project, which is unfortunate since long-term planning benefits greatly from political stability, and many areas are seeing large shifts for the worse in that regard.
It’s an extremely poor example. It’s a multi phase project and for many years government didn’t provide any funding as it was not a priority. It’s not like they were actively trying to build it for 47 years, they built multiple small parts of it through multiple phases but they were never trying to build the whole thing. It was just not anything important to complete.
What if sections will be needed now, and it's easy enough to make a plan to eventually connect all of the parts as needed? Get the zoning work done to prevent anything over 2 stories tall being built over the planned route, and then build the various sections as needed/as budget is available. I'm not saying that's what happened, but I can see smart, modular, as-needed infrastructure projects being drawn out over decades like this.
China has had more than 150 modern bridges collapse. Some of them collapsed in less than a year. China is not building or maintaining bridges any better than the US.
The Brno main post office building here in the Czech Republic has been built as a modular structure that can be moved and reassembled once the new main railway station is completed.
That was in 1937 - the new main railway station does not exist yet (though it looks like it might actually be built this time) and post even moved out of the historic building last year. :P
Makes me wonder how much effort went into mothballing partial construction and then unwinding all of that to get it going again. Seems like it would have cost a lot.
A lot of the reason for the lengthy construction times in cathedrals and churches was the amount of hand-skilled craftsmanship associated with marble, wood, and stone carving and artistry.
